Less than a week before Election Day, the presidential race between President Barack Obama and Republican challenger Mitt Romney is closer than it's ever been in Pennsylvania, a new Franklin & Marshall College poll shows.

The poll, released this morning, shows Obama with a 4-point lead over Romney among likely voters in the state. Obama led Romney by 9 percentage points in the college's September poll.

"(Romney) was on his way to losing the election, but his performance in the debates really changed that," said Madonna, who heads F&M's Center for Politics and Public Affairs.

The latest F&M poll found that Romney's popularity rose to 43 percent, from 34 percent in September.

"Romney has had success with the message he's been delivering — showing more empathy to people who are out of work," Madonna said.

Another reason for Romney's surge, according to the poll, is that voters believe he is more prepared to fix the country's economic problems.

"The economy is bad and people still believe we're mired in it, which hurts Obama and helps Romney," Madonna said.

At stake are Pennsylvania's 20 electoral votes, tied with Illinois for the fifth-largest haul.

The release of the F&M poll coincides with an announcement from two super PACs supporting Romney that the groups will blanket Pennsylvania with advertisements during the campaign's final week.

Obama's advisers said Monday that the Obama campaign also would spend advertising money in the state between now and Election Day.

While Romney has made some progress with Pennsylvania voters, Madonna said he's not sure if it's enough to overcome Obama's lead.

"No one knows if the ads will be enough to sway the race in Romney's favor," Madonna said. "It's doable, but it's still a tough hurdle."

The F&M poll still shows Obama leading as he seeks voters' approval for a second term, with 49 percent among likely voters to Romney's 45 percent. Four percent were undecided.

The margin of error in the survey of 547 likely voters is plus or minus 4.2 percentage points.

Among all registered voters surveyed from Oct. 23 through Sunday, Obama led by 4 points, 48 percent to 44 percent, with 5 percent undecided. A September F&M poll of registered voters had Obama leading by 11 points.

The margin of error in the new poll of all 849 registered voters — 427 Democrats, 317 Republicans and 105 belonging to another party or unaffiliated — is plus or minus 3.4 percentage points.

The shift in the F&M survey reflects many national polls that show the presidential candidates in a dead heat.

A survey by the Pew Research Center found Obama and the former governor of Massachusetts both supported by 47 percent.

An ABC News/Washington Post tracking poll also had the race a dead heat at 49 percent for both candidates.

"Every poll shows movement that is directly traceable to (Romney's) performance in the debates," Madonna said. "The momentum built up after the first debate and continued to climb."

The F&M poll also found Democratic U.S. Sen. Bob Casey maintaining a 10-point lead over Republican Tom Smith.

Other statewide polls released earlier this month suggested the race between Casey and Smith might tighten before Election Day.

"What happened there is that for weeks Casey allowed Smith's campaign to define him — he was painted as ineffective," Madonna said.

But, with only a few days before the election, it seems likely that Casey will keep his Senate seat.

"Casey was able to turn things around by pouring money into ads telling people what he's done," Madonna said.